Ventilating system.



g. M. SURPRISE.`

VENTILATING SYSTEM.

APPLICATION FILED SEPT. 12, 1910.

1,033,963.A Patented July 30,1912.

ma MSE/.. @mwm 'UNiTED sTATEs PATENT oEEioE.

EDWIN M. SURPRISE, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO AMERICAN TELE- PHONE AND 'TELEGRAPH`C9MPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF NEW YORK.

VlEllll'TILA'lINGrl SYSTEM.

Specication of Let-ters Patent.

A Patented July 30, 1912.

Application filed September 12, 1910. Serial No. 581,571. K

To alt Fal1/wml it may concern.:

Be itl known that I, EDWIN M. SURPRISE, residing at Boston, in the county of Sufolk and State of Massachusetts, have invented -certain Improvements in Ventilating .Sys-

' nection with a series of telephone booths.

It has for its chief objects the provision of means for preventing the transmission of sound through the ventilating system from one booth or compartment to another, wit-heut interfering with the eiiiciency of such system.

In the accompanying drawings, in which the same characters of reference are applied to like parts throughout, Figure 1 shows the improved system applied to telephone booths, parts being broken away; Fig. 2 is a partial section on the line 2 2 of Fig. 1,

and Fig. 3 is an enlarged sectional detail showing one of the baliietubes removed from its side extend branch conduits 13, one for each booth. In many situations it is convenient to place the main conduit at the rear of the booths; the branch conduits are therefore shown as horizont-al, having an elbow 1l from which a short vertical connection 15 leads through the top ofthe booth. The air discharged from each branch conduit strikes a suitable delector 16, and passing down through the booth enters the space between the double walls by means of ad justable slides 17 at the bottom of the inner wall, and escapes through a similarly controled opening 17n at the top of the outer Wal Such a system as has just been described is effective in supplying fresh airto the booths, but the conduits act. as channels by which the voices of the telephone users freely travel, resulting in cross-talk, which destroys the privacy ofthe booths and intertenes with the .satisfactory use of the instruments. To prevent this, l provide means ineach of they branch conduits for dissipating the sound waves. To enable -the invention to be readily embodied in existing systems, I prefer to construct lthis sol-md dissipating means as a unit. Since a branch conduit of a definite sectional area has been found most eiiicient for .the ventilation of the standard booth, and since it is customarily may be standard, and each consist-,of a cylindrical tube or sleeve 18, the external diameter of which is such that it will snugly lit Within a conduit 13. The ends of the tubes are shown as beveled at 19 between the inner and outer Walls. Each contains a Series of partitions or battle-plates 20, four being a suitable number, Which project alternately from opposite sides past. the axis so that the ends overlap one another. They arepreferably uniformly inclined to the aXis of the tube, all extending in the same direction and furnishing a tortuous passage. Both tube and partitions are of non-resonant material; the former may be of paper o1` indurated fiber and the latter of rubber or felt. A softmaterial is preferably employed for the baffles, since it is important that they7 shall not only be non-resonant, but also that at least their edges shall be of such a accid character that the passage of the air current over them is inaudible. l prefer to assemble these elements by means of slots 21 formed in the wall of the tube in the proper position, into which the partitions are cemented or otherwise secured.

Une of the units is placed in each branch conduit, as clearly appears in Figs. 1 and 2 of the drawings, with the partitions inclined in the direction of the Ventilating current, or diverging from the conduit walls toward t-he booths. The introduced air passes freely through the conduits into the booths, as indicated by the feathered arrows in Figs. 2 and 3, the partitions o'ering little resistance. to movement in this dlrection. Sound waves, however, proceeding from any booth and passing the elbow 14 impinge against the baiiies, andby these are reHect-ed outwardly t0 the wall of the tube, where they are again reflected against the baffles and finally encounter the succeeding waves. This action is shown by the plain arrows in- Fig. 3. By the reflections and by mutual 'in the form of a cylindrical pipe, these units non-resonant material of the tube and battles absorbs and prevents the direct transmission' of sound through the tube, and the soft edges of the partitions are free from vibration under the influence of the Ventilating current and produce no Whistlin sound. The tapered ends 19 of the tues" 18 act to the same end, avoiding the sound which would result from angular projections, and these features, together with the absence of moving elements in the conduits, prevent the introduction of all objectionable noise'.

Having thus described my invention, I claim: f

1. A sound dissipating device comprising a tube having' its ends tapered between the inner and outer Walls, and partitions extending across thel tube,- both the tube and partitions being o non-resonant material.

2. A sound dissipating device comprising a tube the Wall of which is continuous and provided with slots, and baille-plates secured in the slots.-

3. Sound dissipating means -for a ventii lating conduit consisting of baille-plates projecting partly across the conduit and having accid edges over which the air current passes.

In testimony'whereof, I have signed my name to this speciiication in the presence of two subscribing Witnesses,-this ninth day of September 1910.

EDWIN M, SURPRISE.

`i/Vitnesses:

JOSEPH A. GATELY, FRANK C. LooKWooD. 

